1. Field of the Invention
The present invention generally relates to electronic apparatus and, in a preferred embodiment thereof, more particularly relates to apparatus and methods for dissipating component operating heat in electronic devices such as computers.
2. Description of Related Art
As the increasingly popular notebook computer continues to be provided with higher speed electronic components and correspondingly greater computing power and functionality, the need to sufficiently dissipate operating heat from high heat generating components in the computer becomes correspondingly greater.
As conventionally constructed, a notebook computer has a base housing, within which the primary heat generating components (such as the computer""s microprocessor) are disposed, and a substantially thinner display lid housing pivotally connected to the base housing with a hinge structure. One previously proposed solution to this heat dissipation problem has been to utilize a heat pipe structure to transfer operating heat from a component within the computer base housing, such as the microprocessor, to the display lid housing for dissipation therefrom to ambient when the computer is operating and the lid housing is in its open position.
Previously proposed heat pipe-based structures used to perform this base-to-lid heat transfer function have been incorporated in or positioned adjacent the computer lid hinge structure for relative pivotal movement between base and lid portions of the heat transfer structure in response to the opening and closing of the lid. These previously utilized heat pipe-based heat transfer structures have typically carried with them the undesirable characteristics of complexity, relatively high weight and cost, and rather involved assembly requirements.
A need thus exists for an improved heat pipe-based hinge area heat transfer apparatus and associated methods that eliminate or at least substantially minimize these disadvantages. It is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, specially designed heat transfer apparatus is provided which is representatively useable to transfer operating heat from an electronic component disposed within a housing portion of an electronic apparatus, such as a portable computer, to a lid portion pivotally mounted on the housing for dissipation from the lid portion.
The heat transfer apparatus is of a quite simple construction and basically comprises two thermosyphoning heat pipes. The first heat pipe has a first longitudinal portion, and a second longitudinal portion helically coiled about an axis and defining a generally tubular structure having an interior side surface. Preferably, the first heat pipe, which illustratively has a square cross-section, has a flat outer side surface portion that defines the interior side surface of the generally tubular structure. The second heat pipe has a first longitudinal portion coaxially and rotatably received in the generally tubular structure in heat transfer engagement with its interior side surface, and a second longitudinal portion disposed exteriorly of the generally tubular structure.
Representatively, the heat transfer apparatus is incorporated in a portable computer, illustratively a notebook computer, having a base housing with a heat-generating component therein (representatively a microprocessor), and a lid housing structure secured to the base housing for pivotal movement relative thereto about a hinge line axis. The first longitudinal portion of the first heat pipe is held in thermal communication with the heat-generating component within the base housing, the generally tubular structure is supported in a coaxial relationship with the hinge line, and the second longitudinal portion of the second heat pipe is carried by the lid housing structure in thermal communication with a portion thereof. As the lid housing is opened and closed, the first longitudinal portion of the second heat pipe is rotated within the coiled, generally tubular portion of the first heat pipe. During operation of the computer, operating heat from the microprocessor is transferred to a portion of the lid housing, for dissipation from the lid housing, sequentially via the first longitudinal portion of the first heat pipe, the generally tubular structure, the first longitudinal portion of the second heat pipe, and the second longitudinal portion of the second heat pipe.
In accordance with another aspect of the invention, a special method is used to easily and quickly fabricate the heat transfer apparatus. From a broad perspective, such method comprises the steps of providing a first thermosyphoning heat pipe; helically coiling a first longitudinal portion of the first thermosyphoning heat pipe about an axis to form a generally tubular structure having an interior side surface; providing a second thermosyphoning heat pipe; and positioning a first longitudinal portion of the second thermosyphoning heat pipe coaxially within the generally tubular structure, in slidable heat transfer contact with the interior side surface thereof, for rotation relative to the generally tubular structure about its axis.
Representatively, the first thermosyphoning heat pipe has a flat side surface portion, and preferably has a square cross-section. According to a further aspect of the invention, the method further comprises the step, performed prior to the insertion of the first longitudinal portion of the second heat pipe into the interior of the generally tubular structure, of radially outwardly deforming the interior side surface of the generally tubular structure relative to its outer side surface to increase the inner diameter of the generally tubular structure.
Representatively, this radially outwardly deforming step includes the steps of restraining the outer side surface of the generally tubular structure against radial enlargement thereof while axially forcing a diametrically oversized cylindrical structure through the interior of the generally tubular structure, thereby desirably increasing the circularity of the inner side surface of the generally tubular structure and correspondingly increasing the overall heat transfer contact area between the inner side surface of the generally tubular structure and the first longitudinal portion of the second thermosyphoning heat pipe.
In a preferred embodiment of this fabrication method, the method further comprises the step of providing a cylindrical mandrel having a first longitudinal portion and a second, larger diameter portion. The helically coiling step is performed by helically coiling the first longitudinal portion of the first thermosyphoning heat pipe around the first longitudinal portion of the cylindrical mandrel, and the restraining step is performed by coaxially inserting the generally tubular structure into a tubular restraining member configured to closely receive it. The radially outwardly deforming step includes the steps of forcing the second, larger diameter mandrel portion coaxially through the interior of the previously formed generally tubular structure while using the contact between the generally tubular structure and the tubular restraining member to prevent radial enlargement of the outer side surface of the generally tubular structure. After these steps are performed, the first longitudinal portion of the second heat pipe is coaxially and rotatable inserted into the interior of the generally tubular structure in sliding heat transfer engagement with its radially expanded inner side surface.